Weft feeder with magnet supporting plate provided with an annular groove acting as element for centering and retaining the drum and as thread stopping barrier

Abstract: The weft feeder comprises a fixed body (11), a rotatable disk (12) which winds a reserve of turns (S) on a fixed drum (13), and a fixed magnet supporting plate (14) which supports the drum and is rigidly coupled to the fixed body (11) by means of permanent magnets (15-16). The magnet supporting plate (14) has an annular perimetric blind groove (17) which receives the base (13a) of the drum (13) in order to center and retain it, and acts as a barrier against the accidental passage of the turns of thread into the fixed body (11) of the feeder.

Description: The present invention relates to a weft feeder for weaving looms and other textile machines, and more precisely to a weft feeder of the type comprising a fixed drum on which a movable hollow arm, associated with a rotatable disk driven by an equally hollow drive shaft, winds multiple turns of thread which form a reserve of weft for said loom or the like. A weft feeder of this kind in described e.g. in FR-A-2 127 934 and WO 92/01101. In weft feeders , the rotatable disk is arranged at the base of the fixed drum and is interposed between the fixed body of the feeder and a drum supporting plate which is mounted so that it can rotate freely on the drive shaft of the disk and is held in position by the action of permanent magnets which cooperate with magnets of opposite polarity which are supported by the fixed body; in the present description, said drum supporting plate is referenced as magnet supporting plate. In conventional weft feeders, the edge of the base of the drum externally surrounds the magnet supporting plate so that, as will become apparent hereinafter, an annular gap for connection to the inside of the fixed body of the feeder is delimited between the base of the drum and the rotatable disk. If the weft feeder is installed in areas where aspirating and/or blowing machines operate, or more generally is located in the presence of air jets typically used for cleaning, the turns wound on the drum can partially unwind from said drum, slip to its base and accidentally enter the fixed body of the feeder, passing through said annular gap. This is a severe drawback, since the thread can form tangles and jam the rotatable disk and/or the mechanisms arranged on the fixed body. A principal aim of the present invention is essentially to eliminate this and other drawbacks, and within the scope of this general aim said invention has the important and particular object of providing a weft feeder with a magnet supporting plate and a drum associated with said plate which are shaped and mutually arranged so as to prevent the thread, when affected by an air jet, from entering the fixed body of the weft feeder. With this aim, these and other objects in view, the invention provides a weft feeder provided with a magnet supporting disk and with a drum having the characteristics specified in the appended claims. Substantially, according to the invention, the magnet supporting plate is provided with an annular perimetric blind groove which accommodates the base of the drum to retain and center it. The groove is larger than the edge of the drum, so as to delimit a blind channel for accommodating and retaining the thread that slips towards the base of the drum, so that said groove acts as a barrier preventing said thread from accidentally passing inside the fixed body of the weft feeder. Further characteristics and advantages of the invention will become apparent from the following detailed description and with reference to the accompanying drawings, wherein: figure 1 is a partially sectional view of a conventional weft feeder; figure 2 is an enlarged-scale view of a detail of figure 1, illustrating the typical drawback of the conventional weft feeder of figure 1; figure 3 is an enlarged-scale detail view, similar to figure 2, illustrating the innovative arrangement according to the invention, which is suitable to eliminate the drawback shown in figure 2. With reference to figures 1 and 2, the reference numeral 10 designates a weft feeder of a known type, which comprises a fixed body 11, a rotatable disk 12 associated with a hollow arm that winds a plurality of turns S of thread on a fixed drum 13, and a so-called magnet supporting plate 14 for supporting the drum 13. The plate 14 is rotatably mounted on the drive shaft (not shown) of the disk 13 and is kept motionless, rigidly coupled to the fixed body 11, by the action of permanent magnets 15 which are supported by said plate and cooperate with magnets 16 of opposite polarity supported by the fixed body 11. The fixed drum 13 substantially comprises a dome-shaped element made of sheet metal of adequate thickness, and in the conventional arrangement of figure 1 the edge 13a of the base of the drum externally surrounds the magnet supporting plate 11, as clearly shown in the detail view of figure 2. Accordingly, in conventional weft feeders an annular gap L is delimited between the base of the drum 13 and the rotatable disk 12, and through said gap the turns S that slip off the drum, typically due to the action of an air jet, can pass inside the body 11, following the path indicated by the arrows of figure 2. Figure 3 illustrates the innovative arrangement according to the invention, which is suitable to prevent the passage of the turns into the body 11 as mentioned above. For this purpose, according to the present invention the magnet supporting plate 14 is provided with an annular perimetric blind groove 17 which receives the edge 13a of the base of the drum 13 in order to retain and center said drum; the drum 13 and the plate 14 are permanently connected by spot-welds, by glueing, or by equivalent fixing means. As clearly shown in figure 3, the transverse and axial dimensions of the groove 17 are greater than the thickness and axial depth, respectively, of the edge 13a of the drum, so as to delimit a blind channel 18 for accommodating and retaining the turns of thread that may slip off said drum. Accordingly, the groove 17 acts as a barrier against the accidental penetration of thread inside the body 11 of the feeder. In order to facilitate the accommodation of the thread in the channel 18, the groove 17 has a guiding flared portion 17a at its outer edge. The present invention naturally covers embodiments achieving equal utility by using the same innovative concept defined by the appended claims. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: Weft feeder (10) of the type comprising a fixed body (11), a rotatable disk (12) which winds a reserve of turns (S) on a fixed drum (13), and a fixed magnet supporting plate (14) which supports the drum and is rigidly coupled to the fixed body (11) by means of permanent magnets (15-16), characterized in that the magnet supporting plate (14) has an annular perimetric blind groove (17) which receives the base (13a) of the drum (13) in order to center and retain it, said groove further acting as a barrier against the accidental passage of the turns of thread into the fixed body (11) of the feeder. Weft feeder according to claim 1, characterized in that the transverse and axial dimensions of said groove (17) are larger than the corresponding dimensions (thickness and axial depth) of the edge (13a) of the drum (13), so as to delimit a blind channel (18) for accommodating and retaining the turns of thread which slide at the base of said drum. Weft feeder according to claims 1 and 2, characterized in that said groove (17) has, at its outer edge, a flared portion (17a) for guiding the entry of the thread in said blind channel (18).

Inventors: PEDRINI GIOVANNI, ZENONI PIETRO, PEDRINI, GIOVANNI, ZENONI, PIETRO
Applicants: LGL ELECTRONICS SPA, L.G.L. ELECTRONICS S.P.A.
Application year: 1994
Main classification: D03D47
IPC codes: D03D47